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Flashcards in biology chapter 7 Deck (69)
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1

nervous system

enables organisms to receive and respond to stimuli from their external and internal environments

2

neurons

are the functional units of the nervous system

3

dendrites

are cytoplasmic extensions that receive information and transmit it toward the cell body

4

cell body (soma)

contains the nucleus and controls the metabolic activity of the neuron

5

axon

is a long cellular process that transmits impulses away from the cell body

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myelin

insulating substance that cover axons, which allow axons to conduct impulses faster

7

oligodendrocytes

produce myelin in the central nervous system

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schwann cells

produce myelin in ther peripheral nervous sytem

9

nodes of Ranvier

the gaps between segments of myelin

10

synapse

or synaptic cleft, which is the fap between the axon terminals of one cell and the dendrites of the next cell

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action potentials

impulses that travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse

12

resting potential

when a neuron is at rest, the potential difference between the extracellular space and the intracellular space

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typical resting membrane potential

is -70 millivolts (mV) which means that the inside of the neuron is more negative than the outside

14

minimum threshold membrane potential

(usually around -50 mV) is the level at which an action potential is initiated

15

repolarization

returns the cell to a more negative potential

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refractory period

immediately following an action potential, it may be very difficult or impossible to initiate another action potential

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synapse

the gap between the axon terminal of one neuron and the dendrites of another neuron

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neurotransmitters

the nerve terminal contains thousands of membrane bound vesicles full of chemical messengers

19

curare

blocks the post synaptic acetylcholine receptors so that acetylcholine is unable to interact with the receptor. This leads to paralysis by blocking nerve impulses to muscles

20

botulism toxin

prevents the release of acetylcholine from the presynaptic membrane and also results in paralysis

21

anti-cholinesterases

are used as nerve gases and in the insecticide Parathion. As the name implies, these substances inhibit the activity of the acetylcholinesterase enzyme. As a result the acetylcholine is not degraded in the synapse and continues to affect the post-synaptic membrane. therefore, no coordinated muscular contractions can take place

22

afferent neurons

neurons that carry sensory information about the external or internal environment to the brain or spinal cord

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efferent neurons

neurons that carry motor commands from the brain or spinal cord to various parts of the body

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plexus

a network of nerve fibers

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ganglia

clusters of neuronal cell bodies

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central nervous system

consists of the brain and spinal cord

27

brain

the brain is a mass of neurons that resides in the skull. Its functions include interpreting sensory information, forming motor plans, and cognitive function (thinking). The brain consists of an outer portion called the gray matter (cell bodies) and an inner white matter (myelinated axons). the brain can be divided into the forebrain, midbrain, and hindbrain)

28

forebrain (prosencephalon)

the forebrain consists of the telencephalon and the diencephalon

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cerebral cortex

which is the highly convoluted gray matter that can be seen on the surface of the brain

30

olfactory bulb

is the center for reception and integration of olfactory input